TNF-related apoptosis-inducing ligand (TRAIL; Apo2L) is an endogenous protein that selectively induces apoptosis in cancer cells. TRAIL is a powerful inducer of apoptosis in a wide range of human cancer cell lines via pro-apoptotic death receptor 4 (DR4; TRAIL-R1) and death receptor 5 (DR5; TRAIL-R2) at the cell surface through engagement of the extrinsic or intrinsic apoptotic pathways. TRAIL plays a direct role in tumor suppression during immune surveillance but this anti-tumor mechanism is lost during the disease progression. The ability of TRAIL to initiate apoptosis selectively in cancer cells has led to ongoing clinical trials with administration of recombinant TRAIL and the longer-lived TRAIL-agonist antibodies targeting either of its two pro-apoptotic death receptors.
Despite its potency, recombinant TRAIL has efficacy-limiting properties such as short serum half-life, stability, cost, and delivery. Delivery of recombinant TRAIL or TRAIL-agonist antibodies to the brain is limited by inability of recombinant TRAIL and TRAIL-agonist antibodies to cross the blood-brain barrier. Accordingly, there is a continuing need for anti-cancer compositions and methods.